metal in my airbox

[Boomer84]

Lots of metal in my airbox, dies anyone know where this could be coming from? The filter is fine with no metal in it so must be from the engine? I've just changed the oil so going to put it through a filter to see if there is any metal in that too.

[His Dudeness]

That's an odd one. Don't see how it could be from the engine but some of it might have been sucked into the engine. Maybe someone drilled a screw out of the airbox and left the debris. Is there any signs of damage around any of the screw holes?

[richfzs]

How can it be from the engine, unless you'd been running it backwards for miles?

[Boomer84]

Well I just don't know but when you have a box that's closed at one end (filter essentially means it's closed as the metal couldn't get through it) then it had to come from the open end.

Carbs? I've got them out so I'll take a look today.

[darrsi]

You have a rat or a robin with a drug issue! 


Metal in the airbox would be a tad noticeable i reckon!

[darrsi]

How can it be from the engine, unless you'd been running it backwards for miles?

First dibs if he ever sells it, it's only done -32,000 miles. 

[Fazerider]

That stuff does look like swarf from drilling. Any idea what it is, i.e. is it magnetic? Is more of it near one particular carb inlet?


It's not impossible for debris to make its way "backwards". I had a CG125 that became an absolute bastard to start… on investigating I found the choke flap had broken off the butterfly, the flap itself was in the air box and the steel pivot rod was in the exhaust pipe (the piston and cylinder head had a lot of dings, but the valves and seats had survived somehow).
Do your carbs look OK inside?


If it is from the engine itself it must have been running like a bag of spanners. I doubt if it's possible for the timing chain to slip enough teeth for valves to collide with the piston yet the engine still be capable of running. Perhaps a failed inlet valve spring could do it… would work ok at low revs, but wouldn't close quick enough further up the rev range causing collisions with the piston and blowing the debris back up the intake. All a bit hypothetical really, let us know what you find!

[fazersharp]

Could it be from an old ---(crappy) airfilter that has broken down as they have a metal mesh outer dont they

[Boomer84]

Just an update, the carbs were fine and I see no sign that chunks of metal have gone through them. I cleaned out the airbox and have been riding for a bit so we'll do regular checks. I think it must have been drilling debris from the previous owner.

Well let you know if anything returns

[Rexr]

Could it be from an old ---(crappy) airfilter that has broken down as they have a metal mesh outer dont they

Agreed.....